With the new version 6 comming and the fact that you release new versions much faster now, it would really help to have a way to automatically update clients.

Chrome is a very good example for this. It's always the latest version without anybody needing to install an update. This is how they do it:
You need to have two clients installed. While the user uses client A you can update client B in the background. When the program is started the next time, client B will be started instead of client A. Which makes it possible to update client A.

One problem is, that the client will run with user privileges and you'll need an admin context to update the other client. That's why you'll need an update service running as local system service. This way you won't see any Windows UAC.

Another problem might occur in multi-server-environments, where one client connects to multiple servers with different versions. I think you should add an option to the client configuration wizzard where the update server can be set. Leave it empty and no automatic updates will occur.

Finally the server will have to provide client setup files, somehow. This should be easy though, as you use the same setup files for servers and clients. Just store the setup somewhere the server can find and serve it.

I really hope that you consider this feature. Updating all clients is a real burden! And with that frequency of releases I'll lose my head =D

Maybe there could be a litte update note under the main menu when the client version is older than the server version.
With a click on this note a dialog shows up with some little bit of information and an install button which starts a setup of the exact same version which the sever has.
The administrator would only have to update the server and all clients get the notification about a version change and the chance to update to the excact version the admin has installed.

I don't care if you download the setup files on each client from the web, but maybe the server could hold the setup files and share them with the clients ;) this may reduce traffic and problems with clients connected via VPN and without internet connection.